HVAC & Air

Source & Development at NASA Ames

Traditionally wind tunnels were built with 90 degree mitered joints and turning vanes. Early wind tunnel tests showed that drag was higher than usual. The engineers studying the data claimed the wind tunnel flow was too turbulent and falsely indicated high drag. They found the cross section of the plane could be improved if they could follow the Area rule. The whole design came back to NASA Ames for evaluation. In order to avoid turbulence NASA appropriated research to fix the flow quality in the wind tunnel. That led to the requirement to get rid of the turning vanes. There are a number of possibilities to come up with a laminar flow solution.

A number of small plastic models were built using a water tunnel at the University of Santa Clara. Movies were taken which indicated none of the designs avoided the separated flow issues which were the source of turbulence. The CRV®﻿ was then created to rotate the flow in the elbow to compensate the uneven centrifugal forces.

In the meantime the wind tunnel at NASA Ames was expanding from a 120 x 80 foot cross section to a 200 foot wide cross section and increased wind speed by adding four 75,000 hp electrical fans.

To further improve flow quality a heat exchanger was added, but the air flow through the expansion caused a jet to impinge on the heat exchanger and so flow was very uneven across it. That is where we discovered the geometry of the LAD®﻿ for uniform flow into an expansion. Again that was thoroughly tested at different speeds and the plastic model was constructed by NASA Ames and tests were also done at the University of Santa Clara.

The flow quality improvement has had dramatic effects on the subsequent test results in the wind tunnel.﻿

CRV® ﻿flow conditioner was originally invented at NASA Ames Research Center for sensitive air flow application in R&D research air chamber. CRV® ﻿eliminates noise, vibration, and flow disturbances allowing for accurate measurements and increase in system efficiency.﻿ ﻿CRV® ﻿flow conditioner﻿ has also been applied to the HVAC and heat exchanger industry. ﻿﻿